Film thickness uniformity improvement using edge ring and bias electrode geometry

ABSTRACT

Embodiments of the present disclosure generally relate to the fabrication of integrated circuits and to apparatus for use within a substrate processing chamber to improve film thickness uniformity. More specifically, the embodiments of the disclosure relate to an edge ring. The edge ring may include an overhang ring.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. patent application Ser. No.16/939,898, filed Jul. 27, 2020, which is herein incorporated byreference in its entirety.

BACKGROUND Field

Embodiments of the present disclosure generally relate to thefabrication of integrated circuits and to apparatus for use within asubstrate processing chamber to improve film thickness uniformity.

Description of the Related Art

A primary goal of substrate processing is to obtain the largest usefulsurface area, and as a result the greatest number of chips, possiblefrom each substrate. Some factors to consider include processingvariables that effect the uniformity and thickness of the layerdeposited on the substrate, and contaminants that can attach to thesubstrate and render all or a portion of the substrate useless.Controlling these factors maximizes the useful surface area for eachsubstrate processed.

Recent developments in semiconductor processing have caused interest innew treatment applications that require low ion current and high ionenergy. This enables deep treatment without growing a film. To satisfythe low ion current and high ion energy requirement, bias powerexceeding source power by 10-20 times or more has been used. With such ahigh bias-to source power ratio, the plasma density and the plasmacurrent to the substrate is affected. The affected plasma current anddensity result in film thickening toward the substrate edge.

Edge rings have traditionally been used to improve film thicknessuniformity by altering the deposition rate near an edge of a substrate.However, typical edge rings still result in poor uniformity anddeposition rates near the extreme edges of the substrate. Accordingly,there is a need in the art for edge rings that produce higheruniformity.

SUMMARY

Embodiments of the present disclosure generally relate to an apparatusfor improving the film thickness near an edge of a substrate when duringlow ion current and high ion energy applications.

In one embodiment, an apparatus for substrate processing includes anedge ring and an overhang ring. The edge ring includes a bottom surface,an upper surface, and a groove disposed in the upper surface. Theoverhang ring is disposed in the groove and includes a first portionextending from the groove and a second portion connected to the firstportion and extending radially inward.

In another embodiment, an apparatus for substrate processing includes anedge ring and an overhang ring. The edge ring includes a bottom surface,an upper surface, a central opening, and a groove disposed in the uppersurface. The overhang ring is disposed in the groove and includes afirst portion extending upwards from the groove and a second portionextending radially inward toward a central axis of the overhang ring.

In yet another embodiment, an apparatus for substrate processingincludes an edge ring and an overhang ring. The edge ring furtherincludes a support surface, an upper surface, groove disposed in theupper surface, and a plurality of tabs disposed on the upper surface.The overhang ring is disposed in the groove and further includes a firstportion extending from the groove and a second portion connected to thefirst portion and extending radially inward.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments and are therefore not to be considered limiting ofits scope, and may admit to other equally effective embodiments.

FIG. 1 is a schematic cross sectional view of a process chamber.

FIGS. 2A-2B are cross sectional views of edge rings for use within theprocess chamber of FIG. 1.

FIG. 3A is a schematic plan view of the edge ring of FIG. 2B.

FIG. 3B is a schematic cross sectional view of the edge ring of FIG. 2B.

FIG. 4 is a cross sectional view of an overhang ring utilized with theedge ring of FIGS. 3A-3B.

FIG. 5A-5B are partial cross sectional views of the edge ring of FIGS.3A-3B.

FIG. 6 is a graph illustrating the film thickness over a substrate usingtwo different edge rings.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

FIG. 1 is a schematic cross sectional view of a process chamber 100. Theprocess chamber 100 is an Inductively Coupled Plasma (ICP) chamber. Theprocess chamber 100 includes an inductive coil 114, a lid 104, a firstRadio Frequency (RF) power source 116, a chamber body 102, a pedestalassembly 106, a substrate 126, an edge ring assembly 138, and a secondRF power source 128. The first process chamber is capable of generatinga plasma therein. The plasma includes a first plasma region 120surrounded by a second plasma region 122 of lower plasma density. Thefirst plasma region 120 and/or the second plasma region 122 electricallycouple to the ground via a plurality of RF current lines 124.

The inductive coil 114 is disposed on the lid 104 of the process chamber100. The inductive coil 114 is centered around the central axis 1 of theprocess chamber 100. The inductive coil 114 transmits the source powerfor the process chamber 100. The source power is an RF power, receivedfrom the RF power source 116. The inductive coil receives an RF power ofabout 50 W to about 500 W for transmission to the interior of theprocess chamber 100. In some embodiments, the inductive coil can receivean RF power of about 50 W to about 250 W, such as about 50 W to about200 W, such as about 50 W to about 150 W, such as about 75 W to about150 W, such as about 100 W. The first RF power source and the inductivecoil 114 are connected by a first connection 132 at one end of theinductive coil 114. The first connection 132 may be one or more wires orcables.

The inductive coil 114 may additionally be attached to a secondconnection 134. The second connection 134 is similar to the firstconnection 132. The second connection is connected to ground 118.Connecting the second connection to ground 118 connects the inductivecoil 114 to ground.

The electrostatic chuck 110 is powered by the second RF power source128. The second RF power source 128 produces the bias power for theprocess chamber 100. The second RF power source 128 can produce an RFpower of about 500 W to about 3000 W to be applied to the electrostaticchuck 110. In some embodiments, the second RF power source 128 canproduce an RF power of about 600 W to about 2500 W, such as about 700 Wto about 2250 W, such as about 750 W to about 2200 W, such as about 800W to about 2000 W to be applied to the electrostatic chuck 110. Thesecond RF power source 128 and the electrostatic chuck are connected bya third connection 130. The third connection 130 may be one or morewires or cables.

The lid 104 is a dielectric lid. The lid 104 is disposed on and coversthe top of the process chamber 100. The lid 104 separates the inductivecoil 114 from the processing region 150. The lid may be removable or maybe hinged (not shown). The processing region 150 is within the chamberbody 102 and is defined as the region within the chamber body 102 andthe lid 104. The processing region 150 includes the pedestal assembly106 for supporting a substrate 126 and an edge ring assembly 138. Thefirst plasma region 120 and the second plasma region 122 are containedwithin the processing region 150 when generated.

The pedestal assembly 106 includes a support body 108, an electrostaticchuck 110, a second RF power source 128, and the edge ring assembly 138.The electrostatic chuck 110 is disposed on top of the support body 108.The electrostatic chuck 110 is sized to be disposed on top of thesupport body 108 and receives the substrate 126 on the top surface ofthe electrostatic chuck 110. The edge ring assembly 138 is disposed overthe support body 108 and part of the electrostatic chuck 110. The edgering assembly 138 is disposed around the substrate 126.

The edge ring assembly 138 surrounds the substrate 126. The edge ringassembly 138 includes an overhang ring 112 and an edge ring 140. Theoverhang ring 112 and the edge ring 140 are described in greater detailherein.

The first plasma region 120 is a region of high density plasma withinthe processing region 150. The second plasma region 122 is a region oflow density plasma within the processing region 150. The second plasmaregion 122 surround the first plasma region 120 and has a lower plasmadensity than the first plasma region 120. The first and second plasmaregions 120, 122 may be oxygen based plasmas. The oxygen based plasmasmay be used when performing treatments that include silicon oxides, suchas silicon dioxide.

The plurality of RF current lines 124 represent the communicationbetween the substrate 126 surface and the sidewalls of the chamber body102. The RF current lines 124 in embodiments using previous edge rings,do not pass through either of the first or the second plasma regions120, 122 during low pressure ICP substrate processing. However, edgerings, such as the edge ring assembly 138 and other edge ring assembliesdescribed herein alter that RF current lines 124 near the edge of thesubstrate, such that the RF current lines pass through the first and thesecond plasma region 120, 122. The RF current lines 124 are redirectedby the edge ring assembly 138 as current will pass through the path ofleast resistance. Not to be bound by theory, it is believed the edgering assembly 138 obstructs a path of lesser resistance from thesubstrate to the sidewalls of the chamber body 102. The RF current lines124 are then forced up through the first and the second plasma regions120, 122. This effect may be more pronounced when utilizing relativelyhigh bias powers. The RF current lines 124 passing through the first orthe second plasma region 120, 122 reduce film thickening near asubstrate 126 edge.

FIGS. 2A-2B are cross sectional views of edge ring assemblies 138 a, and138 b used within the process chamber 100 of FIG. 1. The edge ringassemblies 138 a, 138 b are disposed on over and around the outer edgeof the electrostatic chuck 110, as shown in FIG. 1. The edge ringassemblies 138 a, 138 b include two different embodiments of edge rings140 a, 140 b. The first embodiment of the edge ring assembly 138 a,illustrated in FIG. 2A, includes a first edge ring 140 a having a mainbody 250 a. The first edge ring 140 a includes a main body 250 a, acantilever 208 disposed radially inward of the main body 250 a, an outerbody 202 disposed radially outwards of the main body 250 a, and aplurality of vertical protrusions 206 disposed on top of the main body250 a.

The first edge ring 140 a of FIG. 2A is one continuous (e.g.,monolithic) body. The first edge ring 140 a includes a main body 250 athat is vertically extended. The extended main body 250 a extends froman outer body 202. The outer body 202 is cylindrical and is the part ofthe first edge ring 140 a which is disposed adjacent to theelectrostatic chuck 110. The outer body 202 has a bottom surface 240.The bottom surface 240 is adjacent to the top surface of theelectrostatic chuck 110. The bottom surface 240 includes a step 242radially inward of the outer body 202. The step 242 corresponds to andengages with a similar stepped portion of the electrostatic chuck 110.

The outer body 202 further includes a radially inward cantilever 208.The cantilever 208 is the innermost portion of the edge ring 140 a. Thecantilever 208 is disposed adjacent to a substrate support surface 230of the electrostatic chuck 110. The cantilever 208 has a top cantileversurface 232 that is parallel to the substrate support surface 230. Thetop cantilever surface 232 may be substantially coplanar with thesubstrate support surface 230. In some embodiments, the top cantileversurface 232 is utilized to protect the underside of an edge of thesubstrate, such as the substrate 126. The edge of the substrate 126 mayextend over at least a portion of the cantilever 208 during processing.

The main body 250 a has a height H1. The height H1 of the extended mainbody 250 a may be about 10 mm to about 40 mm, such as about 15 mm toabout 35 mm, such as about 20 mm to about 30 mm. In some embodiments,the height H1 of the extended main body 250 a is about 25 mm. Theextended main body 250 a has an inner surface 222 and an outer surface218. In some embodiments, the height H1 is the height of the innersurface 222 of the extended main body 250 a. The inner surface 222extends from the top cantilever surface 232 to the bottom of thevertical protrusion 206.

The inner surface 222 is the surface of the extended main body 250 aclosest to the central axis of the edge ring assembly 138 a. The outersurface 218 is the surface of the extended main body 250 a furthest fromthe central axis of the edge ring assembly 138 a. The extended main body250 a additionally includes an upper surface 220. The upper surface 220connects the inner surface 222 and the outer surface 218. There is avertical protrusion 206 disposed on top of the upper surface 220. Thevertical protrusion 206 has a protrusion inner surface 216. Theprotrusion inner surface 216 is coplanar with the inner surface 222 ofthe extended main body 250 a. There may be a plurality of verticalprotrusions 206 disposed on the extended main body 250 a. The pluralityof vertical protrusions 206 are disposed evenly about the upper surface220 of the edge ring 140 a.

FIG. 2B illustrates an edge ring assembly 138 b according to a secondembodiment. The second edge ring assembly 138 b includes a second edgering 140 b and an overhang ring 112, such as the overhang ring 112 shownin FIG. 1 disposed within a groove 306. The edge ring assembly 138 b mayalso be used in the processing chamber 100 of FIG. 1. The second edgering 140 b of FIG. 2B is one continuous edge ring.

The second edge ring 140 b includes a groove 306 formed in an uppersurface of the main body 250 b. The groove 306 is sized to receive anoverhang ring 112. The outer body 202 has a bottom surface 240. Thebottom surface 240 is adjacent to the top surface of the electrostaticchuck 110. The bottom surface 240 includes a stepped region 242. Thestepped region 242 corresponds to and engages with a similar steppedportion of the electrostatic chuck 110. The outer body 202 furtherincludes a cantilever 208. The cantilever 208 is the most radiallyinward portion of the edge ring 140 b. The cantilever 208 is disposedadjacent to a substrate support surface 230 of the electrostatic chuck110. The cantilever 208 has a top cantilever surface 232 that isparallel to the substrate support surface 230. The top cantileversurface 232 may be substantially coplanar with the substrate supportsurface 230. In some embodiments, the top cantilever surface 232 isutilized to protect the underside of an edge of the substrate, such asthe substrate 126. The edge of the substrate 126 may extend over atleast a portion of the cantilever 208.

There is a vertical protrusion 206 disposed on a top the outer body ofthe second edge ring 140 b. The vertical protrusion 206 has a protrusioninner surface 216. The protrusion inner surface 216 intersects the topcantilever surface 232 of the cantilever 208. There may be a pluralityof vertical protrusions 206 disposed on the top cantilever surface 232.The plurality of vertical protrusions 206 are disposed evenly about thesecond edge ring 140 b.

The groove 306 of the edge ring 140 b is disposed radially outward ofthe cantilever 208 with respect to the central axis of the edge ring 140b. The groove 306 is disposed radially outward of the verticalprotrusion 206. The groove 306 is sized to receive an overhang ring 112.The groove 306 has an inner sidewall 254, an outer sidewall 252, and abottom surface 256. The outer and inner sidewalls 252, 254 are verticalsidewalls, and are a parallel to one another, while being perpendicularto the bottom surface 256. The outer and inner sidewalls 252, 254 arespaced less than about 25 mm from each other, such as less than about 20mm from each other, such as less than about 15 mm from each other. Insome embodiments, the outer and inner sidewalls 252, 254 are spaced thesame distance apart from each other as the width of a first portion 210of the overhang ring 112. The outer and inner sidewalls 252, 254 areparallel with one another and form concentric rings about the centralaxis of the edge ring 138 b. The outer and inner sidewalls 252, 254 areconnected by the bottom surface 256.

The overhang ring 112 includes a first portion 210 and a second portion270. The first portion 210 extends from the groove 306 in an upwardsdirection. In some examples, the first portion 210 is a vertical portionand extends vertically from the groove 306 of the second edge ring 140b. The height H2 of the first portion 210 is about 20 mm to about 40 mm,such as about 20 mm to about 35 mm, such as about 25 mm to about 30 mm.The second portion 270 extends radially inward toward the central axisof the edge ring 138 b. The second portion 270 is disposed at an angleto the first portion 210. In the embodiment described in FIG. 2B, thesecond portion 270 is a horizontal portion and is normal to the firstportion 210 of the overhang ring 112. The second portion 270 is disposedat the distal end of the first portion 210.

The second portion is disposed on top of the first portion 210 and has athickness of about 2 mm to about 8 mm, such as about 3 mm to about 7 mm,such as about 4 mm to about 6 mm, such as about 4.5 mm to about 5.5 mm.

The second portion may be disposed at a height H2 from the bottom of thegroove 306. The second portion may additionally be defined as being aheight H3 from the top of the vertical protrusions 206. The height H3 isabout 10 mm to about 30 mm, such as about 15 mm to about 25 mm, such asabout 17.5 mm to about 22.5 mm. In some embodiments, the height H3 isabout 18 mm to about 20 mm.

It is imagined that embodiments wherein either the first portion 210 isnot a vertical portion or the second portion 270 is not a horizontalportion are possible. In embodiments wherein the first portion 210 isnot a vertical portion or the second portion 270 is not a horizontalportion, the angle between the first and second portions 210, 270 mayvary.

The first portion 210 and the second portion 270 of the overhang ring112 are continuous with one another. In some embodiments, the entiretyof the first portion 210 and the second portion 270 are formed from acontinuous piece of quartz.

The inner overhang surface 214 is the radially inward edge of the second(e.g., horizontal) portion 270. The inner overhang surface 214 isdisposed above the protrusion inner surface 216, such that the secondportion 270 of the overhang ring 112 extends at least partially over thevertical protrusions 206. In some embodiments, the inner overhangsurface 214 may have a similar radial position, such as within +/−10millimeters as the protrusion inner surface 216. In some embodiments,the inner overhang surface 214 extends over only part of the verticalprotrusions 206 and the inner overhang surface 214 is disposed radiallyoutward of the protrusion inner surface 216. The inner overhang surface214 has an inner radius less than the inner radius of the edge ring 140b, such that the inner overhang surface 214 does not extend over asubstrate, such as the substrate 126, to allow placement of thesubstrate within the central opening of the edge ring 138 b.

In embodiments described herein, the entirety of both the edge rings 140a, 140 b and the overhang ring 112 are a quartz material, such assilicon oxide (e.g., SiO₂). Each of the edge rings 140 a, 140 b and theoverhang ring 112 may be made completely of quartz. In some embodiments,only parts of the edge rings 140 a, 140 b and the overhang ring 112 area quartz material and other materials may also be utilized.

The first and second embodiments of the edge ring assemblies 138 a, 138b may share some components not explicitly stated herein. For example,the first and second embodiments of the edge ring assemblies 138 a, 138b include similar outer bodies 202, vertical protrusions 206,cantilevers 208, bottom surfaces 240, and stepped regions 242.

FIG. 3A is a schematic plan view of the edge ring 140 b of FIG. 2B. FIG.3B is a schematic sectional view of the edge ring 140 b of FIG. 2B. Theedge ring 140 b includes a central opening 302, the outer body 202, theplurality of vertical protrusions 206, the groove 306, the topcantilever surface 232, an intermediate surface 316, and an outer ledgesurface 308.

The opening 302 is circular and formed through the center of the edgering 140 b. In some embodiments, the diameter of the opening 302 isabout 295 mm to about 300 mm, such as about 296 mm to about 298 mm, suchas about 297 mm to about 298 mm. The diameter of the opening 302 isslightly less than the diameter of a substrate being processed, suchthat the cantilever 208 is disposed slightly beneath the substrate andprotects the backside of the substrate.

The top cantilever surface 232 is disposed radially outward from theopening 302, such that the top cantilever surface 232 is the surfacebetween the inner cantilever surface 310 of the edge ring 140 b and theintermediate surface 316. The outer edge of the top cantilever surface232 has a diameter of about 315 mm to about 335 mm, such as about 320 mmto about 330 mm such as about 322 mm to about 328 mm. The top cantileversurface 232 is a horizontal surface and is planar.

The plurality of vertical protrusions 206 are formed on top of the topcantilever surface 232. In some embodiments, the plurality of verticalprotrusions 206 are disposed on the outer portion of the top cantileversurface 232. The inner protrusion inner surface has an inner diameter ofabout 300 mm to about 315 mm, such as about 300 mm to about 310 mm, suchas about 302 mm to about 310 mm, such as about 302 mm to about 308 mm.The plurality of vertical protrusions 206 have a protrusion outersurface 502. The protrusion outer surface has a diameter of about 315 mmto about 335 mm, such as about 320 mm to about 330 mm. The plurality ofvertical protrusions 206 includes six protrusions. In some embodiments,the number of vertical protrusions 206 may be 3 protrusions to 12protrusions, such as 3 protrusions to 10 protrusions, such as 4protrusions to 9 protrusions, such as 4 protrusions to 8 protrusions.The vertical protrusions are spaced evenly about the central axis 1 andare equidistant from one another about the top cantilever surface 232.The plurality of vertical protrusions 206 may have a width W of about 5mm to about 25 mm, such as about 5 mm to about 20 mm, such as about 10mm to about 15 mm. The width W is the distance across the face of thevertical protrusion 206 facing the central axis 1. The verticalprotrusions 206 facilitate securing and alignment of a substrate duringprocessing.

The intermediate surface 316 is the surface between the top cantileversurface 232 and the groove 306. The intermediate surface 316 is anangled surface, such that the intermediate surface 316 slopes downwardas the radial distance from the central axis 1 increases.

The groove 306 is disposed between the intermediate surface 316 and theouter body 202. The groove 306 has two sidewalls 252, 254. The innersidewall 254 is adjacent and connected to the intermediate surface 316.The outer sidewall 252 is adjacent and connected to the outer body 202.The inner sidewall 254 of the groove 306 has a diameter of about 325 mmto about 350 mm, such as about 330 mm to about 350 mm, such as about 335mm to about 345 mm. The outer sidewall 252 of the groove 306 has adiameter of about 340 mm to about 360 mm, such as about 345 mm to about355 mm. The groove 306 is formed around the entirety of the edge ring140 b.

In some embodiments, the groove 306 may be a discontinuous groove. Inthis embodiment, the overhang ring 112 would have a first portion 210 tofit into the discontinuous groove. Alternatively, the overhang ring 112and the edge ring 140 b could be adapted to attach the overhang ring 112and the edge ring 140 b using a fastener, sonic welding, or an adhesive.The edge ring 140 b and the overhang ring 112 could also be to be onecontinuous component or part. This embodiment could utilize threedimensional printing or molding to form the overhang ring 112 and theedge ring 140 b.

The outer body 202 has an outer ledge surface 308. The outer ledgesurface 308 is the outermost surface of the edge ring 140 b. The outerledge surface 308 may be a vertical surface and may be part of the outerbody 202. The outer ledge surface 308 of the edge ring 140 b has adiameter of about 375 mm to about 425 mm, such as about 380 mm to about415 mm, such as about 385 mm to about 405 mm, such as about 390 mm toabout 400 mm.

FIG. 3B is a cross sectional side view of the edge ring 140 b. The edgering 140 b includes the opening 302, the outer body 202, the pluralityof vertical protrusions 206, the groove 306, the inner cantileversurface 310, and the outer ledge surface 308. The cross sectional viewof FIG. 3B is taken along the dotted line shown in FIG. 3A.

The edge ring 140 b includes a central axis, which, when the edge ring140 b is positioned in the process chamber 100 of FIG. 1, is coaxialwith the central axis 1. The central axis 1 passes through the opening302.

FIG. 4 is a cross sectional side view of an overhang ring 112 utilizedwith the edge ring 140 b of FIGS. 3A-3B. The overhang ring 112 includesa first portion 210 and a second portion 270. The overhang ring isinserted into the groove 306 of the edge ring 140 b. The overhang ring112 is also centered along the central axis 1. In some embodiments, thecentral axis is the central axis 1 of the edge ring 140 b or the centralaxis 1 of the overhang ring 112. There is an opening 302 formed in theoverhang ring 112, such that the central axis 1 passes through theopening 302.

The first portion 210 includes an inner surface 408 and an outer surface412. The inner surface 408 and the outer surface 412 are connected onone end by a bottom surface 410. Both of the inner surface 408 and theouter surface 412 are vertical surfaces, such that the inner surface 408and the outer surface 412 of the first portion 210 extend upwards. Theinner surface 408 and the outer surface 412 are parallel to each other.The inner surface 408 and the outer surface 412 extend in a similar andupward direction from the bottom surface 410.

The inner surface 408 has a diameter of about 325 mm to about 350 mm,such as about 330 mm to about 350 mm, such as about 335 mm to about 345mm. The outer surface 412 has a diameter of about 335 mm to about 365mm, such as about 340 mm to about 360 mm, such as about 345 mm to about355 mm.

The second portion 270 includes a lower surface 406, a top surface 404,an inner overhang surface 214, and the outer surface 412. The lowersurface 406 of the second portion 270 intersects and is connected to theinner surface 408 of the first portion 210. The outer surface 412extends from the first portion 210 to the second portion 270 and formsthe outer surface 412 of the second portion 270. The top surface 404intersects and connects to the outer surface 412. The top surface is theupper surface of the overhang ring 112. The inner overhang surface 214is the innermost surface of the overhang ring 112. The inner overhangsurface 214 intersects and connects the lower surface 406 and the topsurface 404 of the second portion 270 of the overhang ring 112.

The inner overhang surface 214 is parallel to the inner surface 408 andthe outer surface 412 of the first portion 210. The inner overhangsurface 214 has a diameter of about 300 mm to about 315 mm, such asabout 300 mm to about 310 mm, such as about 302 mm to about 310 mm, suchas about 302 mm to about 308 mm, such as about 303 mm to about 306 mm.The inner overhang surface 214 may be sized to allow a substrate havinga diameter of 300 mm to pass through the opening 302 between the inneroverhang surface 214.

The top surface 404 of the second portion 270 of the overhang ring 112and the lower surface 406 of the second portion 270 of the overhang ring112 are parallel. The perpendicular between the top surface 404 and thesecond portion 270 is about 2.5 mm to about 7.5 mm, such as about 3 mmto about 7 mm, such as about 3.5 mm to about 6.5 mm, such as about 4 mmto about 6 mm. The perpendicular represents the thickness of the secondportion 270. The inner overhang surface 214 has a length of about 2.5 mmto about 7.5 mm, such as about 3 mm to about 7 mm, such as about 3.5 mmto about 6.5 mm, such as about 4 mm to about 6 mm.

The top surface 404 and the lower surface 406 of the second portion 270of the overhang ring 112 may be perpendicular to the inner overhangsurface 214 and the outer surface 412. The top surface 404 and the lowersurface 406 of the second portion 270 of the overhang ring 112 extendradially inwards from the first portion 210 of the overhang ring 112.The lower surface 406 of the second portion 270 of the overhang ring 112is smaller than the top surface 404 of the second portion 270 of theoverhang ring 112, such that the surface area of the lower surface 406is less than the surface area of the top surface 404.

The lower surface 406 of the second portion 270 of the overhang ring 112and the inner surface 408 of the first portion 210 of the overhang ring112 intersect at a first corner 412. The first corner 412 is an innercorner of the overhang ring 112 and is at an angle of about 80 degreesto about 100 degrees, such as about 85 degrees to about 95 degrees, suchas about 90 degrees. The first corner 412 is a rounded or beveledcorner. The curve of the first corner 412 may have a radius of curvatureof about 1.5 mm to about 4 mm, such as about 2 mm to about 3.5 mm, suchas about 2 mm to about 3 mm.

The top surface 404 of the second portion 270 of the overhang ring 112and the outer surface 412 of the overhang ring intersect at a secondcorner 414. The second corner 414 is an outer corner of the overhangring 112 and has an outer angle of about 260 degree to about 280degrees, such as about 265 degrees to about 275 degrees, such as about270 degrees. The second corner 414 is a rounded or beveled corner. Thecurve of the second corner 414 have a radius of curvature of about 0.5mm to about 2 mm, such as about 1 mm to about 1.5 mm.

The intersection of the bottom surface 410 with the outer surface 412and the inner surface 408 creates bottom corners 416. The bottom corners416 have a radius of curvature of about 0.5 mm to about 2 mm, such asabout 1 mm to about 1.5 mm. The bottom corners have outer angles ofabout 260 degree to about 280 degrees, such as about 265 degrees toabout 275 degrees, such as about 270 degrees.

FIG. 5A-5B are partial cross sectional views the edge ring 140 b ofFIGS. 3A-3B. FIG. 5A illustrates a close up view of one side of thecross sectional side view of FIG. 3B. FIG. 5B illustrates a close upview of the protrusion inner surface 216 as shown in FIG. 5A.

The portion of the edge ring 140 b shown in FIG. 5A includes the innercantilever surface 310, the cantilever 208, the vertical protrusions206, the intermediate surface 316, the groove 306, the outer body 202,the outer ledge surface 308, the bottom surface 240, and the steppedregion 242. The edge ring 140 b is a single part and is disposed aroundan electrostatic chuck 110 and a substrate 126.

The cantilever 208 is disposed adjacent to the inner cantilever surface310 of the edge ring 140 b. The inner cantilever surface 310 is theinnermost portion of the edge ring 140 b. The top cantilever surface 232is the upper surface of the cantilever 208. The inner cantilever surface310 is the inner surface of the cantilever 208.

The top protrusion surface 530 of the cantilever 208 intersects theprotrusion inner surface 216 of the vertical protrusions 206. Theprotrusion inner surface 216 extends from the top cantilever surface 232to the top protrusion surface 530. The protrusion inner surface 216 isan angled surface and is at an angle greater than 90 degrees withrespect to the top cantilever surface 232. The top protrusion surface530 is a horizontal surface. The top protrusion surface 530 extends fromthe protrusion inner surface 216 to the protrusion outer surface 502.The protrusion outer surface 502 is a vertical surface. The protrusionouter surface extends from the top protrusion surface 530 to theintermediate surface 316. The protrusion outer surface 502 meets the topprotrusion surface 530 on one end and the intermediate surface 316 onthe other end.

The intermediate surface 316 extends from the protrusion outer surface502 to the groove 306. More specifically, the intermediate surface 316extends from the bottom end of the protrusion outer surface 502 to thetop end of the inner sidewall 254 of the groove 306. The intermediatesurface 316 is an angled surface, such that the intermediate surface 316slopes downward as the radial distance from the central axis 1increases. The intermediate surface 316 may be at an angle of about 5degrees to about 15 degrees with respect to the top cantilever surface232, such as about an angle of about 7.5 degrees to about 12.5 degrees,such as about 9 degrees to about 11 degrees.

The groove 306 is disposed between the intermediate surface 316 and theouter body 202. The groove 306 has two sidewalls 252, 254. The innersidewall 254 is adjacent and connected to the intermediate surface 316.The outer sidewall 252 is adjacent and connected to the outer body 202.The inner sidewall 254 and the outer sidewall 252 are verticalsidewalls. The inner sidewall 254 and the outer sidewall 252 areconnected by the bottom surface 256 of the groove 306. The bottomsurface 256 of the groove 306 is a horizontal surface. The bottomsurface 256 of the groove 306 is about 1 mm to about 5 mm below an innerbottom surface 522, such as 1.5 mm to about 4 mm below an inner bottomsurface 522, such as about 2 mm to about 3 mm below the inner bottomsurface 522 or about 2.25 mm to 2.75 mm below the inner bottom surface522.

The inner sidewall 254 is larger than the outer sidewall 252 within thegroove 306. The outer sidewall 252 is smaller than the inner sidewall254 because of the slope of the intermediate surface 316 and the outerbody 202. The bottom surface 256 of the groove is sized to receive thebottom surface 410 of the overhang ring 112.

The outer body 202 includes the inner main surface 508, the outer curvedportion 510, and the outer ledge surface 308. The inner main surface 508is coplanar with the intermediate surface 316, such that the outer body202 has a surface at an angle of about 5 degrees to about 15 degreeswith respect to the top cantilever surface 232, such as about an angleof about 7.5 degrees to about 12.5 degrees, such as about 9 degrees toabout 11 degrees.

The outer ledge surface 308 of the outer body 202 is the outermostsurface of the edge ring 140 b. The outer ledge surface 308 of the outerbody 202 is connected to the inner main surface 508 by the outer curvedportion 510. The outer curved portion 510 connects the outer edge of theinner main surface 508 and the top edge of the outer ledge surface 308.The outer curved portion has a radius of curvature of about 3 mm toabout 10 mm, such as about 4 mm to about 9 mm, such as about 5 mm toabout 8 mm, such as about 6 mm to about 7 mm. The outer ledge surface308 of the outer body 202 extends downward to protect an outer edge ofthe electrostatic chuck 110 (shown in FIGS. 2A-2B).

The outer ledge surface 308 of the outer body 202 is connected to aledge bottom surface 514. The ledge bottom surface 514 is a horizontalsurface. The ledge bottom surface 514 connects the outer ledge surface308 to the inner ledge surface 516. The ledge bottom surface 514 isconnected to the outer ledge surface 308 and the inner ledge surface 516at curved corners. The curved corners between the outer ledge surface308 and the ledge bottom surface 514 as well as the inner ledge surface516 and the ledge bottom surface 514 have a radius of curvature of about0.5 mm to about 2.5 mm, such as about 0.75 mm to about 2 mm, such asabout 1 mm to about 1.5 mm.

The inner ledge surface 516 is a vertical surface and is parallel to theouter ledge surface 308. The inner ledge surface 516 is sized tosurround an outer surface of an electrostatic chuck. The inner ledgesurface 516 is part of the bottom surface 240 of the edge ring 140 b.The inner ledge surface 516 is connected on a first end to the ledgebottom surface 514 and on a second end to the primary bottom surface518.

The primary bottom surface 518 is a horizontal surface. The primarybottom surface 518 is a planar surface and extends from the inner ledgesurface 516 to the lower stepped surface 520. The lower stepped surface520 is a vertical surface that is part of the stepped region 242. Thelower stepped surface 520 is radially inward of the inner ledge surface516 and the primary bottom surface 518. The lower stepped surface 520 isalso radially inward of the groove 306. The lower stepped surface 520connects the primary bottom surface 518 and the inner bottom surface522.

The inner bottom surface 522 is a horizontal surface that connects thelower stepped surface 520 to the inner cantilever surface 310. The innerbottom surface 522 is below the vertical protrusions 206 and thecantilever 208. The inner bottom surface 522 is a planar surface. Theinner bottom surface 522 is part of the stepped region 242.

FIG. 5B illustrates a close-up view of the protrusion inner surface 216.The protrusion inner surface 216 includes a first inner protrusionsurface 528 and a second inner protrusion surface 532. The protrusioninner surface 216 is a curved inner surface. The radius of curvature ofthe protrusion inner surface 216 is about 150 mm to about 165 mm, suchas about 150 mm to about 160 mm, such as about 152 mm to about 158 mm,such as about 154 mm to about 156 mm. The first inner protrusion surface528 is a vertical surface extending from the top cantilever surface 232of the cantilever 208. The first inner protrusion surface 528 isconnected to the top cantilever surface 232 at a first protrusion corner526. The first protrusion 526 corner may be a curved corner, such thatthe first protrusion corner 526 has a radius of curvature of about 1 mmto about 5 mm, such as about 2 mm to about 4 mm. The first innerprotrusion surface 528 has a height H3 of about 1 mm to about 5 mm, suchas about 2 mm to about 4 mm, such as about 2.5 mm to about 3.5 mm.

The second inner protrusion surface 532 is disposed adjacent to thefirst inner protrusion surface 528 and connects to the first innerprotrusion surface 528 at a second protrusion corner 524. The secondinner protrusion surface 532 is a positively sloped surface as thedistance from the central axis increases. The second inner protrusionsurface 532 is offset by an angle θ from a vertical line, such that thesecond inner protrusion surface 532 has an angle θ of about 5 degrees toabout 20 degrees, such as about 7 degrees to about 15 degrees, such asabout 9 degrees to about 12 degrees.

The second inner protrusion surface 532 has a height H4. The height H4of the second inner protrusion surface 532 is about 1 mm to about 4 mm,such as about 1.5 mm to about 3 mm, such as about 2 mm to about 2.5 mm.The second inner protrusion surface 532 is connected to the topprotrusion surface 530 at a third protrusion corner 520. The thirdprotrusion corner 520 is a curved corner, such that the third protrusioncorner 520 has a radius of curvature of about 0.1 mm to about 0.5 mm,such as about 0.2 mm to about 0.4 mm, such as 0.25 mm to about 0.35 mm.

FIG. 6 is a graph illustrating the film thickness over a substrate afterusing two different edge rings during an SiO₂ treatment, such as an SiO₂oxidation process. A first edge ring is a standard edge ring and haspoor thickness uniformity near the edge of a substrate (represented bythe solid line). The second edge ring is an edge ring utilizing anoverhang feature, such as the edge ring 140 b described herein and hasimproved thickness uniformity near the edge of the substrate.

FIG. 6 shows greatly improved layer thickness near the edge of thesubstrate. The improved layer thickness is caused at least in part bythe altering of the direct RF current communication paths, such as theRF currently lines 124 in FIG. 1, between the substrate and thesidewalls of the process chamber. In conventional substrate treatmentprocesses with high bias-to source power ratios, plasma density and theplasma current to the substrate is affected. The affected plasma currentand density result in film thickening toward the substrate edge. Thefilm thickening toward the substrate edge is caused by direct RFcommunication between the substrate and the grounded sidewall, ratherthan through the plasma controlled by the source power coil.

As shown in FIG. 6, utilizing edge rings with overhang rings has beenfound to produce higher uniformity and alter the direct RF communicationpath to pass through the higher density plasma formed by the sourcepower coil. The RF current lines 124 are altered to flow through aplasma, such as the first plasma region and the second plasma region.

The overhang ring changes the paths of the RF current lines 124 to passthrough a region with higher plasma density than would be achieved ifusing a conventional edge ring. The second portion 210 of the overhangring 112 pushes the RF current lines 124 inward so that the RF currentlines 124 pass through a region of higher plasma density and does notsignificantly alter the ion current to the substrate near the edge sincethe first portion 210 of the overhang ring 112 is not disposedimmediately adjacent to the edge of the substrate.

Although both the edge rings 140 a, 140 b and the overhang ring 112 aredescribed herein as being a quartz material, it is contemplated thatother materials could also be used within the edge ring 140 and/or theoverhang ring 112. Other materials which could be a part of the edgering 140 a, 140 b and the overhang rings 112 include silicon carbide,alumina, or yttria. In some embodiments, other ceramic materials areutilized. In some embodiments, the quartz material can includeadditional materials embedded therein.

While some corners of the edge rings 140 a, 140 b and the overhang ring112 are described above as being curved corners, it is contemplated thatall of the corners of the edge rings 140 a, 140 b and the overhang ring112 may be curved corners. Unless otherwise described above, all of thecorners of the edge rings 140 a, 140 b and the overhang ring 112 may bebroken to be curved edges with a radius of curvature of less than about1 mm, such as less than about 0.75 mm, such as less than about 0.5 mm.In an alternative embodiment, all of the corners of the edge rings 140a, 140 b and the overhang ring 112 may be sharp corners.

In some embodiments, the edge ring 140 a of FIG. 2A is utilized. In thisembodiment, an apparatus for substrate processing includes an edge ring.The edge ring includes a bottom surface and an upper surface. The uppersurface further includes a cantilever, a extended main body, and anouter body. The cantilever is disposed radially inward of the extendedmain body and the extended main body is disposed radially inward of theouter body. The extended main body includes an inner surface, an outersurface, and an upper surface. The upper surface includes a verticalprotrusion disposed thereon and the extended main body has a height ofabout 10 mm to about 40 mm.

While embodiments herein generally describe dimensions with respect toprocessing 300 mm substrates, it is contemplated that substrates ofother dimensions may also be processed. In such examples, the dimensionsof the edge rings described herein may be scaled accordingly.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. An edge ring for substrate processing comprising: a bottom surface; an upper surface; an inner surface connecting the bottom surface and the upper surface and forming an opening centered around a central axis; a plurality of protrusions extending from the upper surface and spaced around the opening; and an annular groove formed in the upper surface and extending towards the bottom surface and radially outward from the plurality of protrusions.
 2. The edge ring of claim 1, wherein the annular groove of the edge ring has an inner sidewall and an outer sidewall which are parallel and concentric, both of the inner sidewall and the outer sidewall centered around the central axis.
 3. The edge ring of claim 2, wherein the inner sidewall and the outer sidewall are less than about 20 mm apart.
 4. The edge ring of claim 3, wherein an inner sidewall of the annular groove has a diameter of about 325 mm to about 350 mm.
 5. The edge ring of claim 1, wherein the edge ring comprises a quartz material.
 6. The edge ring of claim 1, wherein the plurality of protrusions comprises 3 to 10 protrusions.
 7. The edge ring of claim 6, wherein a protrusion inner surface has a diameter of about 300 mm to about 315 mm.
 8. The edge ring of claim 7, wherein the protrusion inner surface of each of the plurality of protrusions has a width of about 5 mm to about 25 mm.
 9. The edge ring of claim 1, wherein the edge ring further comprises an outer ledge, the outer ledge extending from the bottom surface of the edge ring.
 10. The edge ring of claim 1, wherein the inner surface has an inner diameter of about 295 mm to about 300 mm.
 11. The edge ring of claim 1, wherein the bottom surface further comprises: an inner bottom surface disposed below the plurality of protrusions; a primary bottom surface; and a lower stepped surface connecting the inner bottom surface and the primary bottom surface.
 12. An edge ring, configured for use during semiconductor manufacturing, comprising: a bottom surface; an upper surface positioned at an angle relative to the bottom surface; an inner surface connecting the bottom surface and the upper surface and forming an opening with a diameter of about 295 mm to about 300 mm centered around a central axis; a protrusion formed in the upper surface; and a groove extending inward from the upper surface towards the bottom surface and radially outward from the protrusion.
 13. The edge ring of claim 12, wherein the bottom surface further comprises: an inner bottom surface; a lower stepped surface connected to an outer edge of the inner bottom surface; a primary bottom surface connected to an opposite end of the lower stepped surface as the inner bottom surface; and an inner ledge surface connected to an outer edge of the primary bottom surface.
 14. The edge ring of claim 13, wherein a bottom surface of the groove is about 1 mm to about 5 mm vertically disposed from the inner bottom surface.
 15. The edge ring of claim 12, wherein the groove is a discontinuous groove.
 16. The edge ring of claim 12, wherein the protrusion is one of a plurality of protrusions.
 17. The edge ring of claim 12, wherein the groove is less than about 15 mm in width.
 18. An edge ring, configured for use during semiconductor manufacturing, comprising: a bottom surface comprising: an inner bottom surface; a lower stepped surface connected to an outer edge of the inner bottom surface; a primary bottom surface connected to an opposite end of the lower stepped surface as the inner bottom surface; an inner ledge surface connected to an outer edge of the primary bottom surface; and a ledge bottom surface connected to the inner ledge surface; an upper surface comprising: a top cantilever surface; a plurality of protrusions extending from the upper surface and spaced evenly about a central axis of the edge ring, the protrusion having a protrusion inner surface which intersects the top cantilever surface and has a protrusion diameter of about 300 mm to about 315 mm; an intermediate surface extending at an angle relative to the top cantilever surface and radially outward of the top cantilever surface and the plurality of protrusions; an inner main surface coplanar with the intermediate surface and radially outward of the intermediate surface; a groove disposed between the intermediate surface and the inner main surface and extending towards the bottom surface, the groove further comprising an inner groove sidewall which intersects the intermediate surface and an outer groove sidewall which intersects the inner main surface, wherein the inner groove sidewall and the outer groove sidewall are spaced less than about 25 mm apart; and an outer ledge surface extending perpendicular to the top cantilever surface and coupled to the ledge bottom surface; and an inner surface connecting the bottom surface and the upper surface and forming an opening with an inner surface diameter of about 295 mm to about 300 mm centered around a central axis.
 19. The edge ring of claim 18, wherein an outer curved portion connects the inner main surface and the outer ledge surface and the inner groove sidewall and the outer groove sidewall are parallel.
 20. The edge ring of claim 18, wherein the protrusion inner surface further comprises: a first inner protrusion surface extending from and perpendicular to the top cantilever surface; and a second inner protrusion surface extending from the first inner protrusion surface and at an angle of about 5 degrees to about 20 degrees outward relative to a vertical formed by the first inner protrusion surface. 